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Date:   Fri, 24 Jul 2020 12:44:09 -0000
From:   "tip-bot2 for Chris Wilson" <tip-bot2@linutronix.de>
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Subject: [tip: sched/urgent] sched: Warn if garbage is passed to
 default_wake_function()
Cc:     Chris Wilson <chris@chris-wilson.co.uk>,
        Ingo Molnar <mingo@kernel.org>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>, x86 <x86@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
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The following commit has been merged into the sched/urgent branch of tip:

Commit-ID:     062d3f95b630113e1156a31f376ad36e25da29a7
Gitweb:        https://git.kernel.org/tip/062d3f95b630113e1156a31f376ad36e25da29a7
Author:        Chris Wilson <chris@chris-wilson.co.uk>
AuthorDate:    Thu, 23 Jul 2020 21:10:42 +01:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Fri, 24 Jul 2020 14:40:25 +02:00

sched: Warn if garbage is passed to default_wake_function()

Since the default_wake_function() passes its flags onto
try_to_wake_up(), warn if those flags collide with internal values.

Given that the supplied flags are garbage, no repair can be done but at
least alert the user to the damage they are causing.

In the belief that these errors should be picked up during testing, the
warning is only compiled in under CONFIG_SCHED_DEBUG.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/20200723201042.18861-1-chris@chris-wilson.co.uk
---
 kernel/sched/core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 5dece9b..2142c67 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4485,6 +4485,7 @@ asmlinkage __visible void __sched preempt_schedule_irq(void)
 int default_wake_function(wait_queue_entry_t *curr, unsigned mode, int wake_flags,
 			  void *key)
 {
+	WARN_ON_ONCE(IS_ENABLED(CONFIG_SCHED_DEBUG) && wake_flags & ~WF_SYNC);
 	return try_to_wake_up(curr->private, mode, wake_flags);
 }
 EXPORT_SYMBOL(default_wake_function);